The invention relates generally to transparency projection and in particular to an apparatus designed to be used in combination with an overhead projector for projecting transparencies.
Transparencies and overhead projectors are widely used today during all sorts of lectures and presentations. In the field of education, courses are taught with the aid of carefully planned, progressive sets of transparencies which are specifically designed for that purpose, and it is usual for one or more such sets to be used at each course lecture. It has been found advantageous to bind each set of transparencies together in the general form of a book to facilitate repeated, sequential viewing. Typically, the bound transparencies are mounted in a folder or between covers for convenient storage.
Although it has been possible to provide inexpensive bound sets of transparencies which are convenient to store and view, it has been necessary also to provide auxiliary devices to receive and retain the transparencies in a stationary position on the display surface or stage of the projector for viewing. Such retaining devices have had to be relatively complex to provide the requisite stability, have often required various mechanisms to fasten them to the projector, and have had an adverse effect on the convenience, utility and cost of bound transparency sets.
Another problem encountered with existing bound transparency sets relates to overlaying a plurality of transparencies to achieve special effects. This requires that the transparencies be retained in close registry. It has been suggested that registry pins be provided for this purpose on the auxiliary retaining devices and that each transparency have apertures to receive the pins. Such an arrangement is inconvenient in use, because the operator often finds himself fumbling in the dark with transparencies in an attempt to place them on or remove them from the registry pins.
It is an object of the present invention to provide an improved apparatus for viewing transparencies on an overhead projector which obviates one or more of the problems found in the prior art.
It is a further object of the invention to provide an apparatus for storing transparencies which may be used to view the transparencies on a projector and which is not physically attached to the projector, yet remains stationary during use.
It is another object of the invention to provide an apparatus for storing transparencies which may be used directly on a projector stage to view the transparencies without any auxiliary retaining means.
It is a further object of the invention to provide a transparency storage and viewing apparatus which is compact and easily portable.
It is a still further object of the invention to provide an apparatus which can hold several transparencies in an aligned configuration so that two or more transparencies can be overlaid for viewing without interfering with the normal viewing operation.
It is also an object of the invention to provide an apparatus of the type described which is convenient and reliable in use, yet relatively inexpensive and simple in construction.
In accordance with an illustrative embodiment of the invention, a transparency storage and display apparatus is provided which incorporates a frame, and the transparencies are retained by a portion of the frame defining a mounting member. Substantially all of the weight of the frame is concentrated in the mounting member and a member in opposed, spaced relationship to the mounting member. Owing to the exceptional stability which results, the apparatus may be used for viewing the transparencies by simply placing it on top of an overhead projector without attachment to the projector. Hence, the single apparatus serves as a compact, portable storage means for the transparencies and, without modification or adjustment, can be used to view the transparencies. The apparatus also includes tabs which extend from the mounting member into the area circumscribed by the frame, in which area the transparencies are stored. These tabs lie in planes normal to the transparencies and are designed to fit into respective slits in the transparencies, so that the transparencies remain in an aligned configuration, which makes it possible to overlay them one upon another rather than viewing them sequentially.
The accompanying drawings illustrate a presently preferred embodiment of the invention and other objects, features and advantages of the invention will become apparent by reading the following detailed description in conjunction with them.